DE 199 13 942 C1 discloses an integrated gas discharge lamp which comprises an integrated ignition device with a toroidal core transformer. The toroidal core transformer is spooled with a secondary winding and then spooled with a primary winding. Since the primary winding, in order to achieve a good coupling of the transformer, covers a large area of the secondary winding, the insulation of the wire of the primary winding must be designed in such a way that it can insulate the entire ignition voltage generated by the secondary winding. However, this is involved and expensive since there are no constructional measures for insulating the voltage, but the insulation of the wire must accomplish precisely this.
DE 10 2004 044 368 A1 discloses an improved ignition transformer, of which the ferrite has a cup core shape and the secondary winding consists of a metal strip. However, this transformer is complex to produce since the secondary winding cannot be wound on the ferrite, but instead has to be wound on a mandrel and can only be inserted into the cup-core-shaped ferrite as a finished coil. Owing to the manufacturing tolerances, the coil space available in this instance is not well utilized and the coupling also is not optimal.